Woody Biomass CHP – “How to”: An Introduction

Woody Biomass CHP – “How to”: An
David Sjoding, Director
Northwest CHP Technical Assistance Partnership
International District Energy Association
Biomass CHP & District Energy Workshop
Seattle, Washington
June 11, 2014
President’s Executive Order 13624:
40GW of new CHP by 2020
• CHP TAPs are critical components of achieving the goal:
– Regional CHP experts
– Provide fact‐based, un‐biased information on CHP
Project development
Project financing
Local electric and natural gas interfaces
State best practice policies
– Vendor, fuel, and technology neutral
CHP Technical Assistance Partnerships
Key Activities
• Market Opportunity Analysis.
Supporting analyses of CHP market opportunities in diverse markets including industrial, federal, institutional, and commercial sectors
 Education and Outreach. Providing information on the energy and non‐energy benefits and applications of CHP to state and local policy makers, regulators, end users, trade associations, and others.
• Technical Assistance.
Providing technical assistance to end‐users and stakeholders to help them consider CHP, waste heat to power, and/or district energy with CHP in their facility and to help them through the development process from initial CHP screening to installation.
What Is Combined Heat and Power?
CHP is an integrated energy system that:
• Is located at or near a factory or building
• Generates electrical and/or mechanical power
• Recovers waste heat for  heating,  cooling or  dehumidification
• Can utilize a variety of technologies and fuels
CHP Recaptures Much of that Heat,
Increasing Overall Efficiency of Energy
75 units
150 units
94 units
56 units
30 units
100 units
Power Plant
32% efficiency
(Including T&D)
Onsite Boiler
80% efficiency
75% efficiency
45 units
Total Efficiency
~ 50%
Total Efficiency
~ 75%
100 units
What Are the Benefits of CHP?
• CHP is more efficient than separate generation of electricity and heat
• Higher efficiency translates to lower operating cost,
(but requires capital investment)
• Higher efficiency reduces emissions of all pollutants
• CHP can also increase energy reliability and enhance power quality
• On‐site electric generation reduces grid congestion and avoids distribution costs
Biomass CHP – In General
• Biomass feedstock • Different feedstocks require different CHP technologies
• Woody biomass – steam turbine generators
• Biomass CHP technology pathways use organic materials more efficiently than electricity generation alone
• Lessons learned from each technology pathway include environmental, economic development, emerging commercialization, and technology applications
Feedstock Perspectives
• Think creatively ̶ What is available locally? • Transportation costs can kill a project. 50‐mile radius is a typical rule of thumb maximum distance • Feedstock Sources?
 Overgrown forests – Fire hazard reduction
 Urban wood waste
• Biomass feedstocks – How reliable is the source? Price? 
Due diligence is needed for a long‐term supply contract Do a biomass availability assessment
Don’t assume it’s there because there is plenty to see – Reliable gathering
It may be necessary to start a company with hands‐on management to develop skills
Feedstock Perspectives (continued)
• What if we lost the supply? How do we manage seasonal variation? Have alternatives.
• Amount stored – How long a supply?
• Feedstock competition is coming as bioenergy technology advances.
• What is the moisture content? It makes a difference in system design.
• What is the quality of the feedstock? Wood chips by hammermill or knife –
avoid clogging of auger (moisture impacts auger design)
Environmental Considerations
• Think through environmental aspects early and deeply – there are a wide variety of topics: Air Quality, water quality, over harvesting the forest, and ash disposal
• Compared to what? This is a basis for showing improvements: Example: Nippon Paper: Fuel oil versus wood waste
• Air emissions – biomass portion of boiler MACT (not CISWI if no MSW)
• Forest Health concerns can be an environmental plus to aid forest health treatments
Environmental Considerations
• Solid waste avoidance – uses for the ash. What are the nutrients?
• Carbon footprint and greenhouse gas reductions : Biogenic carbon (not fossil carbon)
• Water use and quality impacts
• Capture lessons learned and the story behind them
EPA & Biomass
• A number of revised rules are in the works or recently completed: • GHG and biogenic carbon (in process)
• Boiler MACT
• CISWI (Reconsideration 12/2/11 & Final 12/21/12)
• Biomass GHG: How carbon neutral is it? What do you measure? Time span? A tree or a forest?
• Clean cellulosic biomass: Hog fuel, wood pallets, wood pellets fall under CAA section 112 boiler regulations
• Biomass CHP does not fall under the CISWI incinerator rules (Commercial/Industrial Solid Waste Incinerators) unless MSW included in the feedstock
Technology: What Makes a Great Wood
Waste Project?
A great wood waste CHP/district energy project has:
• Proper sizing
• High energy efficiency/Use of thermal energy
• Covered storage area for the feedstock
• Quality requirements for the feedstock
• Strong moisture reduction system
• Strong environmental controls and well‐understood environmental improvements
• Effective/efficient heating
Fuel Drying – Why?
• Significantly improves the efficiency of the boiler or gasifier
• For boiler:
─ 5% to 15% improvements in efficiency (Boiler is not an efficient dryer, so dry fuel before it goes to the boiler.)
─ 50% to 60% more steam production
• Improves combustion
• Reduces air emissions
See Biomass Drying and Dewatering for Clean Heat & Power, 2008, available from the Northwest CHP Technical Assistance Partnership (http://northwestchptap.org/NwChpDocs/BiomassDryingAndDewateringForCleanHeatAndPower.pdf)
Waste Heat Recovery for
Drying Wood Waste
Heat recovery is key to a cost‐effective dryer project
Recover flue gas of power boiler or gasifier
Recover heat from other waste heat sources
Recover heat from dryer exhaust
Design a complete CHP system, including:
Feedstock drying Waste heat recovery
Biomass CHP Design Lessons
• Ensure all parts of the system are properly sized
• Don’t undersize the feed auger
• Ensure boiler sized for both thermal energy and power generation needs
• If twin augers, ensure they rotate counter clockwise to each other – Solves moist wood clumping to one side and the feed rate cut in half
• Does the thermal energy demand vary over time? Use extraction/condensing turbine for thermal flexibility as opposed to a back pressure turbine
• Wood ash settling – Needs a quiet place to settle (no venting)
• Avoid pressure relief valves – Wastes energy
• When power prices are high, avoid thermal energy only systems (do both: CHP)
Biomass CHP Project Profiles
CHPTAPs inform and connect
National Database on DOE AMO site
Example of Biomass CHP System
Cooley Dickinson Hospital in Maine with 140 patient beds 600,000 square feet
Feedstock: Wood chips
500 kW system (2 steam turbines) & 2 boilers with 75 psig for steam distribution throughout the hospital •
Cooling via an absorption chiller
Reasons to choose CHP: Eliminate fuel oil use and improved reliability
Link: http://www.northeastchptap.org/profiles/documents/CooleyDickinso
Steam Boiler/Extraction Condensing
Steam Turbine Generator – 60 MW
• Feedstock: Spent liquor, wood chips/hog fuel with storage
• Steam boiler, recovery boiler (both at 875 psig), steam turbine (triple extraction condensing) & generator
Power sold to California
300,000 tons/yr CO2 reduction
Steam extracted at 3 different psig
Fuel flexibility
• RockTenn Tacoma Kraft –See case study www.northwestchptap.org
Steam Boiler/Backpressure Steam Turbine Generator 1.5 MW
• Cave Junction, OR
• Feedstock: Hog fuel, forest thinnings & logging debris
• Steam boiler (300 psig), steam turbine & generator •
PPA to local utility
Electrostatic precipitator
7,182 MT/yr CO2e reduction
Thermal: Kiln dried lumber
Rough and Ready Lumber, Cave Junction, OR ‐ See case study www.northwestchptap.org
Conclusion & Next Steps
• Economic advantage – make your own power for on‐site use or sell it/wheel it
• Long‐term feedstock supply is crucial
• A long‐term power purchase agreement is helpful
• Quality design is essential
• Use the feedstock efficiently
• BIOMASS CHP: Make good use of the thermal energy and power generation
• The CHP TAP s help with next steps
– CHP screenings (go/no go scan of potential) – Technical assistance
CHP TAP Technical Development
Screening and Preliminary Analysis
Quick screening questions with spreadsheet payback calculator.
Feasibility Analysis
Uses available site information.
Estimate: savings,
Installation costs, simple paybacks, equipment sizing and type.
Investment Grade Analysis
3rd Party review of Engineering Analysis.
Review equipment sizing and choices.
Procurement, Operations, Maintenance, Commissioning
Review specifications and bids,
Limited operational analysis
Questions & Contact Information
Dave Sjoding, Director
Northwest CHP Technical Assistance Partnership www.northwestCHPTAP.org
[email protected]
(360) 956‐2004